Why can't we enter heaven with our physical body?

Question

Why can't we enter the heaven with our physical body? However if some of the sages have entered, who are all? please list them.

If we can't enter with the human body in the hell then so punishment should be only for our jeeva aatma right?

1. We couldn't able to stay in the heaven more than 5 days. Is it true?

2. How many days we need to stay in the hell if we did sin? And return to earth?

Could someone please help me to research on this one.

Answer 1

In general it is impossible for ordinary people to enter heaven like that. But the special cases mentioned by @iammilind are different. There is no Vedic ritual which will enable any Jiva atma to ascend to heaven in sthula sharira under ordinary, mundane causes. But there is a story of Trisanku who does ascend, which is another special case.

Valmiki Ramayana Bala Kanda

tasya buddhiH samutpannaa yajeyam iti raaghava || 1-57-11
gacCheyam sva shariireNa devaanaam paramaam gatim |
vasiSTham sa samaahuuya kathayaamaasa cintitam || 1-57-12

Oh, Raghava, an idea sprang up in the mind of Trishanku to perform a ritual by which he will go to heaven with his own body. Then he sincerely invited Vashishta and told him what his thinking is.

ashakyam iti ca api ukto vasiSThena mahaatmanaa |
pratyaakhyaato vasiSThena sa yayau dakSiNaam disham || 1-57-13
tataH tat karma siddhi artham putraan tasya gato nRipaH |

But the great-souled Vashishta said it as impossible. Thus repudiated Trishanku went to southerly direction in search of orchestrators for the purpose of realizing that task, such a phantasmal ritual that enables him to go to heaven with his body, and that king has gone to the sons of Vashishta.

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sa shariirasya bhadram vaH trihankoH asya bhuupateH |
aarohaNam pratij~naatam na anRitam kartum utsahe || 1-60-27

"'Let safety betide you all. I have promised to this king Trishanku that he will ascend to heaven with his mortal body, and I am not interested to make it untrue.' (Spoken by Vishwamitra to the Gods)

svargo astu sa shariirasya trisha.nkoH asya shaashvataH |
nakSatraaNi ca sarvaaNi maamakaani dhruvaaNi atha || 1-60-28
yaavat lokaa dhariSyanti tiSThanti etaani sarvashaH |
yat kRitaani suraaH sarve tat anuj~naatum arhatha || 1-60-29

"'Let there be eternal heaven to Trishanku with his mortal body. Next, as along as the worlds remain, let all of these stars and galaxies I have created also remain eternally in their places as my creation. It will be apt of you all gods to accede to this.' So said Vishwamitra to gods.

evam uktaaH suraaH sarve prati uucuH muni pu.ngavam |
evam bhavatu bhadram te tiSThantu etaani sarvashaH || 1-60-30
gagane taani anekaani vaishvaanara pathaat bahiH |
nakSatraaNi muni shreSTha teSu jyotiHSu jaajvalan || 1-60-31
avaag shiraaH trishankuH ca tiSThatu amara sannibhaH |

"When all the gods are addressed thus they replied the eminent saint Vishwamitra saying, 'so be it! Safe you be! Let all the created objects prevail in their respective places. Those amazing and numerous stars you have created will remain in firmament, but outside the path of stelliform of Cosmic Person. Trishanku will also remain in the circle of stars you created, but upside-down, for Indra's indict cannot be annulled, and he will be gleaming like a star and similar to any celestial.

There is also a case when King Raivata entered Brahmaloka just like that, with Revati, his daughter, to find a suitable groom for her. This story however, is most commonly used as an example for time dilation, when thousands of years on earth had passed just when it seemed like 20 minutes in Brahmaloka.

Answer 2

"Why can't we enter in the heaven with the human body?"

Followers of Dharma Can enter the heaven with physical body.
There are at least 2 instances.

1. Sudarshana and his granddaughter-wife Oghavati (as half)

   “O Sudarsana! I am Dharma Devata. (Deity of Dharma). I have come to test your mind and your devotion towards guests. Mruthyu is waiting to kill you whenever you transgress dharma. But you conquered Mruthyu. You have already conquered the six rivals viz., Kama, krodha, lobha, moha, mada and matsarya. Your wife is your virtuous follower. You both are eligible to go to higher regions with this physical body whenever you wish. [source]

2. King Yudhishtira

   Shakra said, ‘Thou shalt behold thy brothers in Heaven. They have reached it before thee. Indeed, thou shalt see all of them there, with Krishna. Do not yield to grief, O chief of the Bharatas. Having cast off their human bodies they have gone there, O chief of Bharata’s race. As regards thee, it is ordained that thou shalt go thither in this very body of thine. [source]

Similarly entering the hell with the physical body also should be possible.

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"We couldn't able to stay in the heaven more than 5 days. Is it true? How many days we need to stay in the hell if we did sin? And return to earth?"

There is no stipulated timeline. Once a jeeva(soul)'s karma-phala gathered from past deeds diminish completely, its time in heaven-hell finishes and it has to return to the physical living plane.

BG 9.21 - After having enjoyed that vast heavenly world, they enter into the human world on the exhaustion of their merit. ... [source]